A cruise ship carrying 420 Bermuda-bound passengers was detained at its Alexandria dock several hours last night after the draw span on the Woodrow Wilson bridge refused to open.

An emergency repair effort was completed about 1 a.m. today and the 11,000-ton Caribe passed through the span about 30 minutes later with the cheers of its passengers ringing in the ears of workmen on the bridge. w

The Caribe, a 440-foot long, 70-foot-wide vessel of West German registry, left its pier about 6:30 p.m. to begin a six-day cruise to Bermuda, according to John E. Smith Jr., of the local travel agency chartering the vessel.

As it approached the bridge, at Alexandria's southern tip, the vessel blew its whistles to signal for the movable center segments of the span to be rotated upward.

But, the bridge failed to open enough to permit the Caribe to safely pass through, and instead of proceeding down river toward the Chesapeake Bay and the Atlantic, the vessel returned to its dock.

While waiting in the brightly lit ship, passengers dined, danced and enjoyed free service at the vessel's bars, Smith said.

With an over-water length of about three quarters of a mile, the bridge, which carries the Capital Beltway across the Potomac River, falls into three jurisdictions -- the District, Maryland and Virginia.

Officials of the D.C. Highway Department, which operates the drawbridge mechanism, described the malfunction as an electrical problem, but its exact nature could not be learned immediately.

Despite the delay in passing under the bridge, Smith said he expected the ship to reach Hamilton, Bermuda, on schedule Thursday morning.

He said his firm began last year to offer cruises from Alexandria aboard the vessel, which he described as the largest cruise ship to come up the Potomac.